def createNum():

    print("---start----")
    a, b = 0, 1
    for i in range(5):
        print("----1----")
        yield b
        print("----2----")
        a, b = b, a+b
        print("----3----")
    print("----stop----")


a = createNum()
next(a)
print("----")
next(a)

# 方法二
ret = a.__next__()
print(ret)
print("====")